Nanotribology at Electrodes: Influence of Adsorbates and Potential on Friction Forces Studied with Atomic Force Microscopy

Nielinger, Michael; Hausen, Florian; Podghainiy, Nikolay; Baltruschat, Helmut

doi:10.1002/9783527628513.ch21

Cited by 3 publications

(7 citation statements)

References 11 publications

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“…In our previous experiments, such a large friction value was observed when stepping the potential from a potential of zero Cu coverage into the copper 2/3 adlayer region [ 10 ]. A similar effect was observed previously on Pt(111) during the formation of a copper monolayer [ 11 ]. Bennewitz et al observed such an increase on Au(111) upon Cu adsorption during potential cycling [ 12 ].…”

Section: Resultssupporting

confidence: 86%

“…3 shows the dependency of friction force versus normal load for a set of four selected potentials corresponding to different adsorbate structures. As already reported before [ 11 ], a transition in the coefficient of friction is observed for a copper monolayer at F N = 70 nN. Here, we extended the study to lower normal loads and observed another transition in the friction coefficient at a normal load of F N ≈ 15 nN.…”

Section: Resultssupporting

confidence: 84%

“…Our group recently started to study friction forces on single crystal electrodes under electrochemical conditions. In [ 10 – 11 ] we investigated the effect of copper under potential deposition (UPD) on Au(111) and Pt(111) on friction and found an increase in friction force after adsorption of a sub- or monolayer of copper. A particularly high friction was observed at the potential where the 2/3 Cu adlayer was formed.…”

Section: Introductionmentioning

confidence: 99%

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Stick–slip behaviour on Au(111) with adsorption of copper and sulfate

Podgaynyy¹,

Wezisla²,

Molls³

et al. 2015

Beilstein J. Nanotechnol.

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SummarySeveral transitions in the friction coefficient with increasing load are found on Au(111) in sulfuric acid electrolyte containing Cu ions when a monolayer (or submonolayer) of Cu is adsorbed. At the corresponding normal loads, a transition to double or multiple slips in stick–slip friction is observed. The stick length in this case corresponds to multiples of the lattice distance of the adsorbed sulfate, which is adsorbed in a √3 × √7 superstructure on the copper monolayer. Stick–slip behaviour for the copper monolayer as well as for 2/3 coverage can be observed at F N ≥ 15 nN. At this normal load, a change from a small to a large friction coefficient occurs. This leads to the interpretation that the tip penetrates the electrochemical double layer at this point. At the potential (or point) of zero charge (pzc), stick–slip resolution persists at all normal forces investigated.

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Section: Resultssupporting

confidence: 86%

Section: Resultssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Stick–slip behaviour on Au(111) with adsorption of copper and sulfate

Podgaynyy¹,

Wezisla²,

Molls³

et al. 2015

Beilstein J. Nanotechnol.

Self Cite

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“…In addition, the electrode potential may have a direct or an indirect (by influencing adsorption processes) impact on friction. Therefore, apart from the importance of friction on wet surfaces (and thus electrodes), electrochemistry also offers means to control friction [1–12] . For SILs, Li et al.…”

Section: Introductionmentioning

confidence: 99%

Friction on I‐Modified Au(111) in a Tetraglyme Electrolyte

2022

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In situ electrochemical lateral force microscopy (EC-LFM) has been employed to study the ordered structure of Li + containing tetraglyme (G4) in front of I-modified Au(111) and its influence on friction as function of normal load. Since the effect of water in aprotic electrolytes is a critical issue, the influence of water on the ordered structure and friction was also been investigated. Lateral force maps recorded at low normal load (F N < 30 nN) show that the adsorbed iodine forms a ffi ffi ffi 3 p � ffi ffi ffi 3 p À � R30 � structure (q I ¼ 0:33Þ independent of potential. With increasing normal load, observed atomic corrugations at both potentials (0.45 V and À 0.4 V) are in agreement with the Au(111) (1 � 1Þ structure while returning to a ffi ffi ffi 3 p � ffi ffi ffi 3 p À � R30 � structure with decreasing normal load. Thus we conclude that the AFM tip penetrates into the iodine adlayer without irreversible wear. Astonishingly, no clear friction increase was observed upon penetration into the iodine adlayer; also no corresponding step was found in force separation (FS) curves. On the other hand, FS curves for I-modified Au(111) in pure G4 solvent and Li + containing electrolyte clearly showed several steps suggesting that G4 molecules are forming up to five ordered layers. It is noteworthy that we observed two different push-through forces for the innermost layers. Considering the higher reproducibility of FS curves on I-modified Au(111) compared to bare Au(111) we assume that the low surface energy of the iodine monolayer leads to negligible interaction between G4 molecules and iodine adlayer, resulting in less perturbations of the structure by the solid phase and also an increase of push-through force. Charts of friction forces vs. normal load are found to be independent of applied potential and the concentration of water.

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“…We did not find any indication for that. We had observed previously that for the Au(111)/Cu UPD system local alloy formation induced by wear was only observed when a Pt covered tip was used and the normal load was 1 μN [39] or, for several UPD systems, when scanning with an STM tip under conditions where a quantum nano‐contact is formed [40–42] . But it is also clear that if the tip penetrates the Ag adlayer this is already the first stage of wear; tip induced displacement or local dissolution of Ag, however, does not lead to a structural change, this kind of wear is self‐healing.…”

Section: Resultsmentioning

confidence: 92%

In situ friction study of Ag Underpotential deposition (UPD) on Au(111) in aqueous electrolyte

Park

Baltruschat

2021

ChemPhysChem

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The electrodeposition of silver on Au(111) was investigated using lateral force microscopy (LFM) in Ag+ containing sulfuric acid. Friction force images show that adsorbed sulfate forms ()3×7R19.1∘ structure (θsulfate=0.2) on Au(111) prior to Ag underpotential deposition (UPD) and (3×3R30∘) structure (θsulfate=0.33 ) on a complete monolayer or bilayer of Ag. Variation of friction with normal load shows a non‐monotonous dependence, which is caused by increasing penetration of the tip into the sulfate adlayer. In addition, the friction force is influenced by the varying coverage and mobility of Ag atoms on the surface. Before Ag coverage reaches the critical value, the deposited silver atoms may be mobile enough to be dragged by the movement of AFM tip. Possible penetration of the tip into the UPD layer at very high loads is discussed as a model for self‐healing wear. However, when the coverage of Ag is close to 1, the deposited Ag atoms are tight enough to resist the influence of the AFM tip and the tip penetrates only into the sulfate adlayer.

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Nanotribology at Electrodes: Influence of Adsorbates and Potential on Friction Forces Studied with Atomic Force Microscopy

Cited by 3 publications

References 11 publications

Stick–slip behaviour on Au(111) with adsorption of copper and sulfate

Stick–slip behaviour on Au(111) with adsorption of copper and sulfate

Friction on I‐Modified Au(111) in a Tetraglyme Electrolyte

In situ friction study of Ag Underpotential deposition (UPD) on Au(111) in aqueous electrolyte

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